Evening,
Great question. I assume you are trying to create a justification for two HBA's or for a lower RPO. I have had hundreds of storage failures even on redundant array's and rarely have I run into issues with machines 100% hosed due to this interruption. This is due to the method storage arrays use store and forward. That being said the problems I have seen are 100% on Windows. The file system below Windows is not journaling based and thus suffers badly from these type of crashes. I have seen a Windows machine have to return to a backup due to this type of crash it is rare. I have never had a problem with Linux.
What it really comes down to is design for failure and requirements. Is your business willing to return to a backup from last night due to a driver or single card failure? If the answer is that is too costly or unreasonable then more availablity options via CapEX should be made available. It's not a issue of how much data is lost it's are you willing to loose data.
I hope it helps,
J